Automatic tool changer for machine tool

ABSTRACT

A tool storage drum which is adapted to receive and store a plurality of toolholders is rotatably mounted on top of the upright of a horizontal machining center behind the spindle thereof. A tool changer carriage carrying a tool change arm is pivotally mounted on the upright above the spindle and is pivotable between a parked positon in which an end of the tool changer arm is adjacent to the tool storage drum and an exchange position in which an end of the tool changer arm is adjacent to the spindle. The tool changer arm is slidably mounted on the carriage for movement between an extended and a retracted position to remove toolholders from their sockets or insert them therein and is rotatable through 180° to interchange its ends for the purpose of exchanging a tool in the spindle for a tool previously removed from the tool storage drum.

BACKGROUND OF THE INVENTION

This invention relates to automatic tool changers for machine tools.Many different types of automatic tool changers have been manufacturedin the past, but all have been relatively complex and expensive and haverequired considerable space to accommodate their tool storage magazines.The principle object of this invention is to provide an automatic toolchanger which is simpler, less expensive, more reliable, and whichrequires less space than the automatic tool changers heretofore known inthe art. Other objects and advantages of the invention will be apparentfrom the detailed description herein.

SUMMARY OF THE INVENTION

A tool storage magazine which is adapted to receive and to store aplurality of toolholders is mounted on a frame behind the spindle of amachine tool. A tool changer carriage is pivotally mounted on the framefor movement between a parked and an exchange position. A double-endedtool changer arm is slidably mounted on the carriage for movementbetween an extended and a retracted position and is pivotally mounted onthe carriage for rotation through at least 180° to interchange the endsof the tool changer arm. The tool changer carriage is positioned so thatan end of the tool changer arm is adjacent to the tool storage magazinein the parked position thereof and an end of the tool changer arm isadjacent to the spindle in the exchange position thereof to enabletoolholders to be transferred between the tool changer arm and the toolstorage magazine and between the tool changer arm and the spindle.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a preferred embodiment of theinvention utilized in combination with a horizontal machining center;

FIG. 2 is a front elevational view of the embodiment of FIG. 1;

FIG. 3 is a plan view of the embodiment of FIGS. 1 and 2;

FIG. 4 is a cross-sectional view of the tool storage drum of theembodiment of FIGS. 1 to 3 taken on the line 4--4 of FIG. 5;

FIG. 5 is a plan view of the tool storage drum of the embodiment ofFIGS. 1 to 3 taken on the line 5--5 of FIG. 4;

FIG. 6 is a cross-sectional view of the tool changer arm and toolchanger carriage of the embodiment of FIGS. 1 to 3;

FIG. 7 is a cross-sectional view taken on the line 7--7 of FIG. 6;

FIG. 8 is a side elevational view, partially cut away, taken on the line8--8 of FIG. 7;

FIG. 9 is a side elevational view of the tool changer arm of theembodiment of FIGS. 1 to 3;

FIG. 10 is a plan view taken on the line 10--10 of FIG. 9;

FIG. 11 is a cross-sectional view taken on the line 11--11 of FIG. 9;

FIGS. 12A through 12X are diagrammatic side elevational views of thespindle, tool changer carriage, tool changer arm and tool storage drumof the embodiment of FIGS. 1 to 3 during the individual steps of a toolchange operation; and

FIG. 13 is a fragmentary cross-sectional view taken on the line 13--13of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 3 show a preferred embodiment of the invention which isutilized in combination with a horizontal machining center 10. Machiningcenter 10 includes a first bed 12 which supports a pair of horizontalways 14 upon which a worktable 16 is slidably mounted for movement alonga horizontal Z axis 18. A second bed 20 supports a second pair ofhorizontal ways 22 upon which an upright 24 is slidably mounted formovement along a horizontal X axis 26 (FIG. 2) which is perpendicular toZ axis 18. Upright 24 has a pair of vertical ways 28 upon which aspindlehead 30 is slidably mounted for movement along a vertical Y axis32 which is perpendicular to both Z axis 18 and X axis 26. Spindlehead30 is driven up and down Y axis 32 by a motor 33 which is coupled tospindlehead 30 by conventional means.

A spindle 34 is rotatably mounted on spindlehead 30 and is rotated by amotor 36 which is coupled to spindle 34 by conventional means not shown.Spindle 34 is adapted to receive toolholders 38 carrying tools 40 and toclamp toolholders 38 thereto. Tools 40 rotate with spindle 34 and areused to perform work on a workpiece (not shown) which is supported onworktable 16.

The tool changer includes a circular tool magazine or drum 42 which isrotatably mounted on upright 24 behind spindle 34 and which is adaptedto receive and to store a plurality of toolholders 38. Upright 24 servesas the frame for the tool changer in this embodiment of the invention. Atool changer carriage 44 is pivotally mounted on upright 24 abovespindle 34 for movement between an exchange position shown in solidlines in FIG. 1 and a parked position shown in broken lines at the topof FIG. 1. A double-ended tool changer arm 46 is slidably mounted oncarriage 44 for movement between a retracted position shown in solidlines in FIG. 1 and an extended position shown in broken lines on theleft side of FIG. 1. Tool changer arm 46 is also rotatably mounted oncarriage 44 for rotation through 180° about its own axis to interchangethe two ends 48 and 50 of tool changer arm 46.

Both ends 48 and 50 of tool changer arm 46 are adapted to receivetoolholders 38 and to clamp toolholders 38 thereto. In the parkedposition of tool changer carriage 44, one end of tool changer arm 46 isadjacent to tool storage drum 42 as shown by the broken lines in FIG. 1,and in the exchange position, one end of tool changer arm 46 is adjacentto spindle 34 as shown by the solid lines in FIG. 1. To transfer atoolholder 38 from spindle 34 to tool changer arm 46, or vice versa,tool changer carriage 44 is moved to the exchange position and spindle34 is moved along Y axis 32 to a transfer position shown in FIG. 1 inwhich the adjacent end of tool changer arm 46 is in operativerelationship with spindle 34. To transfer a toolholder 38 from toolstorage drum 42 to tool changer arm 46, or vice versa, tool changercarriage 44 is moved to its parked position and tool storage drum 42 ismoved to a transfer position shown in FIG. 1 in which the adjacent endof tool changer arm 46 is in operative relationship with tool storagedrum 42. Toolholder 38 is then transferred from drum 42 to arm 46 orvice versa. The individual steps of the tool change operation areillustrated in FIGS. 12A to 12X and are described in later paragraphs.

FIGS. 4 and 5 show the details of tool storage drum 42. The toolholders38 are held in a ring of sockets 52 which are bolted to a flattoolholder ring 54. There can be any number of sockets 52 in tool drum42. Toolholder ring 54 is rotatably mounted on upright 24 by means of aguide ring 56 which is bolted to toolholder ring 54 and engages rollers58. Rollers 58 and guide ring 56 have matching V-shaped surfaces whichengage each other as shown in the lefthand portion of FIG. 4. Rollers 58are rotatably mounted on a base plate 60 which, in turn, is slidablymounted on rods 62 which are rigidly attached to the top 25 of upright24 by means of brackets 64 bolted to top 25. Four sleeves 63 are weldedto the bottom of base plate 60 and slidably engage rods 62 to serve as aslidable mounting for base plate 60.

Base plate 60 is slidable between a parked position and a transferposition by means of a hydraulic ram 66 whose body portion is bolted toupright top 25 and whose piston portion is attached to a bracket 68 onthe bottom of base plate 60. When the piston of hydraulic ram 66 isextended, it pushes base plate 60 in a leftward direction as viewed inFIG. 4 to the parked position and when the piston of hydraulic ram 66 isretracted, it pulls base plate 60 in a rightward direction as viewed inFIG. 4 to the transfer position. Toolholder ring 54 and guide ring 56move with base plate 60 between the parked and the transfer positions.Tool drum 42 has a ready station 69 (FIG. 3) at which position toolchanger arm 46 can remove a toolholder 38 from toolholder ring 54. Toremove a selected tool from toolholder ring 54, ring 54 is rotated toplace the selected tool in ready station 69, then tool changer carriage44 and tool changer arm 46 are actuated to remove the selected tool fromready station 69.

A groove 70 is formed in the outer periphery of guide ring 56 and adrive chain 72 is seated in groove 70 and is rigidly attached to guidering 56. Drive chain 72 is engaged by a drive sprocket 74 (FIG. 13)which is rotated by a motor 76 mounted on base plate 60. Motor 76 anddrive sprocket 74 serve to rotate toolholder ring 54 to place anydesired toolholder 38 in position to be transferred to tool changer arm46. Motor 76 is controlled by a conventional motor control circuit whichis not shown in the drawings.

FIGS. 6, 7 and 8 show details of tool changer carriage 44, tool changerarm 46 and the drive means therefor. Tool changer carriage 44 includes aT-shaped housing 78 (FIG. 6) which is attached to two coaxial shafts 80and 82 that are journaled to upright 24 by bearing sleeves 84 and 86 forrotation about an axis 87 which corresponds to the crossbar of saidT-shape. Bearing sleeves 84 and 86 are supported by sockets 88 and 90which are attached to upright 24 by brackets 92 and 94. Shafts 80 and 82are pinned to housing 78 by pins 96 and 98. Housing 78 can be rotatedthrough 120° about the common axis 87 of shafts 80 and 82 to swing toolchanger carriage 44 between its parked and its exchange positions.

A drive gear 100 (FIG. 7) is attached to the outer end of shaft 82 andengages a rack 102 which is driven by a hydraulic ram 104. When thepiston of hydraulic ram 104 is extended, it rotates housing 78 from itsexchange position, shown in solid lines in FIG. 8, to its parkedposition, shown in broken lines in FIG. 8. When the piston of hydraulicram 104 is retracted, it rotates housing 78 from its parked position toits exchange position.

Tool change arm 46 is rigidly mounted on the end of a splined sleeve 106(FIG. 6) which is slidably mounted on a splined shaft 108 for movementbetween an extended and retracted position of tool changer arm 46. Toolchanger arm 46 is shown in its retracted position in FIGS. 6 and 8. Anouter sleeve 110 is rigidly attached to splined sleeve 106 and isslidable in a socket 112 in housing 78. A bracket 114 is rigidlyattached to the front end of outer sleeve 110. A pair of hydrauliccylinders 118 and 120 are mounted on the exterior of housing 78 onbrackets 122 and 124 and have piston rods 126 and 128 which are attachedto bracket 114 for moving tool changer arm 46 between its extended andretracted positions.

For the purpose of rotating tool change arm 46 through 180° tointerchange its ends, splined shaft 108 is journaled in housing 78 bybearings 130 and 132 (FIG. 6) for rotation about axis 133 whichcorresponds to the stem of T-shaped housing 78 and has a gear 134 formedthereon which is driven by a rack 136 (FIG. 7). Rack 136 is formed onthe piston 138 of a hydraulic ram 140 which is formed in housing 78.Piston 138 is slidable in a bore 142 in housing 78 under gear 134. Bore142 has a central opening through which gear 134 extends to engage rack136. The ends of bore 142 are closed by end plugs 144 and 146 whichcontain conventional hydraulic fluid ports and adjustment screws 148 and150 which set the limits of travel for piston 138.

FIGS. 9 to 11 show the details of the clamps on the ends of tool changerarm 46 for gripping toolholders 38. Each clamp is made up of a fixed jaw152 and an L-shaped movable jaw 154 which is pivotally attached to fixedjaw 152 by a pivot pin 156. Both jaws 152 and 154 are recessed at theirends in a semicircular arc to embrace toolholder 38 as shown in FIG. 10.Inserts 158 are mounted on jaws 152 and 154 in position to engage aperipheral groove in toolholder 38 to clamp toolholder 38 therebetweenwhen movable jaw 154 is in the closed position. An alignment key 160 isattached to fixed jaw 152 is position to engage an alignment slot intoolholder 38.

Movable jaw 154 is spring biased in its clamped position by a camassembly which includes a cam plunger 162 having a curved cam surface164, a spring 165, a cam follower pin 166 and adjustment screw 168. Camfollower pin 166 is slidably mounted in a bore 167 in tool changer arm46 and is normally pressed against adjustment screw 168 by pressure fromcam surface 164. Cam plunger 162 is slidably mounted in a bore 163 intool changer arm 46 and is urged toward the right in FIG. 10 by spring165 which is mounted in a housing 170 bolted to the side of tool changerarm 46. The pressure exerted on movable jaw 154 by the above-describedcam assembly holds toolholder 38 clamped therein until the pressure isreleased by moving cam plunger 162 to the left in FIG. 10.

For the purpose of engaging cam plunger 162 for movement, a recess 172is formed therein which is aligned with an opening 174 (FIG. 11) in toolchanger arm 46. When tool changer arm 46 is in its retracted position, apin 176 is engaged in recess 172. Pin 176 is attached to the piston 178of a hydraulic ram 180 mounted on the end of tool changer carriage 44.Hydraulic ram 180 moves pin 176 downwardly in FIG. 11 (to the left inFIG. 10) against the force of spring 165 to unclamp movable jaw 154.

When movable jaw 154 is unclamped, it is forced open by a spring loadedpin 186 (FIG. 10) which bears against movable jaw 154 and moves it tothe unclamped position. The spring 188 which presses against pin 186 isconsiderably weaker than spring 165 and is overcome by the force ofspring 165.

The other end of tool changer arm 46 is identical in structure andfunction with the above-described end and interacts with an identicalhydraulic cylinder 180 on the end of tool changer carriage 44.

The detailed steps involved in transferring toolholders 38 between toolstorage drum 42 and spindle 34 are illustrated in FIGS. 12A through 12X.FIG. 12A shows the relationship of parts during a machining operation. Atoolholder 38a carrying a tool 40a is clamped in spindle 34 while atoolholder 38b carrying the next tool 40b to be used in the machiningcycle is clamped in the distal end 48 of tool changer arm 46. Theproximal end 50 of tool changer arm 46 is empty. Tool changer arm 46 isin its retracted position and tool changer carriage 44 is in its parkedposition. Tool storage drum 42 is in its parked position. Spindle 34 canbe anywhere along the Y axis. The steps involved in replacing toolholder38a with toolholder 38b will be described in numerical sequence asfollows:

1. Spindle 34 is moved to a ready position adjacent to the upper limitof Y axis travel. In this particular example, the spindle ready positionis 5" below the upper limit of Y axis travel.

2. Spindle 34 is keylocked as indicated in FIG. 12B.

3. Tool changer carriage 44 is rotated from its parked position to itsexchange position, as shown in FIG. 12C. At the same time, tool storagedrum 42 is rotated to locate the correct empty tool socket in positionto receive tool 38a when it is removed from spindle 34.

4. Spindle 34 is moved to its transfer position in which the empty end50 of tool changer arm 46 embraces toolholder 38a, as shown in FIG. 12D.

5. The clamp on the end 50 of tool changer arm 46 is closed to grasptoolholder 38a and clamp it to end 50, as indicated in FIG. 12E.

6. The toolholder clamp in spindle 34 is released, as indicated in FIG.12F.

7. Tool changer arm 46 is moved from its retracted position to itsextended position, as shown in FIG. 12G, to withdraw toolholder 38a fromspindle 34.

8. Tool changer arm 46 is rotated through 180°, as shown in FIG. 12H, tointerchange the position of toolholders 38a and 38b.

9. Tool changer arm 46 is moved from its extended to its retractedposition, as shown in FIG. 12I, to insert toolholder 38b into spindle34.

10. The toolholder clamp in spindle 34 is actuated to clamp toolholder38b in spindle 34, as indicated in FIG. 12J.

11. The clamp on the end 48 of tool changer arm 46 is opened to releasetoolholder 38b, as indicated in FIG. 12K.

12. Spindle 34 is moved from its transfer position to its readyposition, as indicated in FIG. 12L.

13. Tool changer carriage 44 is rotated from its exchange position toits parked position, as shown in FIG. 12M.

14. Tool changer arm 46 is moved from its retracted position to itsextended position, as shown in FIG. 12N.

15. Tool storage drum 42 is moved from its parked position to itstransfer position, as indicated in FIG. 12O. An empty toolholder sockethas previously been positioned under end 50 of tool changer arm 46 toreceive toolholder 38a.

16. Tool changer arm 46 is moved from its extended position to itsretracted position, as shown in FIG. 12P, to insert tool 38a into theempty socket.

17. The clamp on the end 50 of tool changer arm 46 is opened, asindicated in FIG. 12Q, to release toolholder 38a.

18. Tool storage drum 42 is moved from its transfer position to itsparked position, as indicated in FIG. 12R.

19. Tool storage drum 42 is rotated, as indicated in FIG. 12S, to placethe next toolholder 38c to be used in the machining cycle opposite theend 50 of tool changer arm 46.

20. Tool storage drum 42 is moved from its parked position back to itstransfer position, as indicated in FIG. 12T, to place toolholder 38c inthe end 50 of tool changer arm 46.

21. The clamp on the end 50 of tool changer arm 46 is closed, asindicated in FIG. 12U, to clamp toolholder 38c in end 50.

22. Tool changer arm 46 is moved from its retracted to its extendedposition, as shown in FIG. 12V, to withdraw toolholder 38c from itsstorage socket.

23. Tool storage drum 42 is moved from its transfer position to itsparked position, as shown in FIG. 12W.

24. Tool changer arm 46 is moved from its extended to its retractedposition, as shown in FIG. 12X. This returns the tool changer to theinitial condition described immediately before step No. 1 of the toolchange cycle and completes the tool change cycle.

Although the illustrative embodiment of the invention has been describedin considerable detail for the purpose of fully disclosing a practicaloperative structure incorporating the invention, it is to be understoodthat the particular apparatus shown and described is intended to beillustrative only and that the various novel features of the inventionmay be incorporated in other structural forms without departing from thespirit and scope of the invention as defined in the subjoined claims.

The principles of this invention having now been fully explained inconnection with the foregoing, we hereby claim as my invention:
 1. In amachine tool having a frame;a spindle rotatably supported by said frameand having means to receive different tools for use in machiningoperations; a tool storage magazine movably supported by said frame andhaving means for carrying a plurality of tools adapted to be operablyreceived by said spindle; a tool changer carrier supported by said framefor pivotal movement about a horizontal axis; tool change arm means fortransferring tools between said magazine and said spindle, said toolchange arm means being journaled in said carrier for rotation about anaxis that is transverse to the axis of pivotal movement of said carrier;gripping means on said tool change arm for gripping the tools that arebeing transferred; means for actuating said carrier in its pivotalmovement for bodily moving said tool change arm in a vertical path oftravel between said magazine and said spindle for transferring the toolstherebetween; means for actuating said tool change arm in its rotarymovement for interchanging the positions of the tools in said grippingmeans; a tool ready station at which said magazine is stopped to orientone of said tools in a predetermined position prior to a magazineshifting operation; means for rotating said magazine for moving aselected tool therein into said tool ready station; a tool exchangeposition laterally spaced from said tool ready station at which saidtool change arm means can operatively grip the selected tool from saidmagazine for transfer to the spindle; and means connected to saidmagazine to shift the magazine laterally in a rectilinear movement forrelocating said selected tool supported in the magazine from said toolready station to the tool exchange position where the selected tool isaligned with the grip of said tool change arm means.
 2. A machine toolaccording to claim 1 wherein said tool storage magazine is locatedbehind said spindle and is inclined downwardly away from said spindle.3. An automatic tool changer according to claim 1 wherein said toolstorage drum includes a tool storage ring, and further comprising:aguide ring attached to said tool storage ring; a base plate slidablymounted on said frame for movement between a parked position and atransfer position; and a plurality of rollers rotatably mounted on saidbase plate and positioned to engage said guide ring to rotatably attachsaid guide ring to said baseplate.
 4. An automatic tool changeraccording to claim 3 and further comprising:a chain attached to theexterior of said guide ring; a sprocket engaging said chain; and meansfor rotating said sprocket to cause said tool storage ring to rotate. 5.A machine tool having a frame;a spindle rotatably supported by saidframe and having means to receive different tools for use in machiningoperations; a tool storage magazine having a plurality of tool carrierswith each carrier being adapted to carry one of the tools to be used insaid spindle; a tool ready station at which said magazine is stopped toorient one of said tools in a predetermined position prior to a magazineshifting operation; means connected to such magazine to rotate themagazine for moving a selected one of said tool carriers into said toolready station; tool change arm means having at least one grip forholding a tool and being movably supported by said frame fortransferring tools between said spindle and said tool storage magazine;a tool exchange position laterally spaced from said tool ready stationat which said tool change arm means can operatively grip a tool fromsaid magazine for transfer to the spindle; and means connected to saidmagazine to shift the magazine laterally in a rectilinear movement forrelocating said tool supported in the magazine from said tool readystation to the tool exchange position where the tool is aligned with thegrip of said tool change arm means.
 6. A machine tool according to claim5 wherein said tool storage magazine is located behind said spindle andis inclined downwardly away from said spindle.
 7. A machine toolaccording to claim 5 including means for rotating said tool change armmeans for interchanging the position of tools in said grip; andmeans forbodily pivoting said tool change arm in a vertical path of travelbetween said spindle and said magazine for transferring toolstherebetween.
 8. An automatic tool changer according to claim 1 whereinsaid tool changer carrier comprises:a T-shaped housing; means pivotallyconnecting said housing to said frame for rotation about an axiscorresponding to the crossbar of said T-shape; a splined shaft rotatablyattached within said housing for rotation about an axis corresponding tothe stem of said T-shape; and means slidably mounting said tool changearm means on said splined shaft for movement between an extended and aretracted position.
 9. An automatic tool changer according to claim 8wherein said means for slidably mounting said tool change arm means onsaid splined shaft comprises:a splined sleeve rigidly attached to thecenter of said arm means perpendicular thereto, said splined sleevebeing slidably mounted on said splined shaft and being engagedtherewith; and hydraulic ram means mounted on said housing and coupledto said splined sleeve for sliding said splined sleeve along its axisbetween an extended and a retracted position.
 10. An automatic toolchanger according to claim 9 and also comprising:a gear on said splinedshaft; a rack engaging said gear; and means for reciprocally moving saidrack to rotate said gear, said splined shaft and said tool change armthrough 180°.
 11. An automatic tool changer according to claim 10wherein said means for reciprocally moving said rack comprises:a bore insaid housing coaxial with said rack; a piston slidably mounted withinsaid bore, said rack being formed in the central portion of said piston;and hydraulic means for reciprocally moving said piston within saidbore.